Summary A point at issue in simultaneous interpreting is the time lag between the speaker of the original and the interpreter. The length of the time lag depends on objective and subjective factors. The objective factors can be described in linguistic terms and are something for the interpreter to go by when timing the moment of transposition. However, the optimum time lag between hearing and interpreting rests also on subjective factors arising from the individuality of the interpreter. An examination of the problem involved in the time lag leads us to a number of well-grounded conclusions of relevance to methodological simultaneous interpreting.